What are the optical properties of feldspar?
What are the optical properties of feldspar?
Mineral Group: Feldspar group, plagioclase series….Anorthite Optical Properties.
| Color / Pleochroism | White, grayish, reddish; colorless in thin section |
|---|---|
| 2V: | Measured: 78° to 83°, Calculated: 78° |
| RI values: | nα = 1.573 – 1.577 nβ = 1.580 – 1.585 nγ = 1.585 – 1.590 |
| Optic Sign | Biaxial (-) |
| Birefringence | δ = 0.012 – 0.013 |
Does feldspar have any special properties?
Most feldspar minerals have a Mohs hardness of approximately 6 to 6.5 and a specific gravity between 2.5 and 2.8. They all have a vitreous luster that is often pearly on cleavage faces.
What are the optical properties of albite?
It is a tectosilicate. Its color is usually pure white, hence its name from Latin, albus….
| Albite | |
|---|---|
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.528–1.533 nβ = 1.532–1.537 nγ = 1.538–1.542 |
| Birefringence | δ = 0.010 |
| 2V angle | 85–90° (low); 52–54° (high) |
What is the difference between alkali feldspar and plagioclase feldspar?
Alkali feldspars can often be distinguished from plagioclase feldspars because most grains of the latter exhibit albite twinning (see above Crystal structure), which is manifested by parallel lines on certain cleavage surfaces, whereas grains of alkali feldspars do not.
What is optical properties of materials?
What is Optical property? The term optical property describes a material’s behavior when electromagnetic radiation (light) is incident on the material’s surface or, in other words, how a material interacts under an incident electromagnetic radiation.
How do you identify alkali feldspar?
What is the transparency of plagioclase feldspar?
Diaphaneity Translucent
| Physical Properties of Plagioclase | |
|---|---|
| Chemical Classification | Silicate |
| Luster | Vitreous. Pearly on some cleavage faces. |
| Diaphaneity | Translucent to transparent |
| Cleavage | Perfect in two directions that intersect at approximately 90 degrees. |
What is alkali feldspar used for?
alkali feldspar, any of several common silicate minerals that often occur as variously coloured, glassy crystals. They are used in the manufacture of glass and ceramics; transparent, highly coloured, or iridescent varieties are sometimes used as gemstones.
